www.austriamicrosystems.com

Revision 1.04

10 - 17

AS1334

Datasheet - D e t a i l e d D e s c r i p t i o n

8 Detailed Description

The AS1334 is a simple, step-down DC-DC converter optimized for powering portable applications that require low

dropout voltages such as mobile phones, portable communicators, and similar battery powered RFID devices. Besides

being packed with numerous features like current overload protection, thermal overload shutdown and soft start,

AS1334 displays the following characteristics:

!

Its operation is based on current-mode buck architecture with synchronous rectification for high efficiency.

!

Allows the application to operate at maximum efficiency over a wide range of power levels from a single Li-Ion bat-

tery cell.

!

Provides for a maximum load capability of 650mA in PWM mode, wherein the maximum load range may vary

depending on input voltage, output voltage and the selected inductor.

!

Is ranked at an efficiency of around 96% for a 400mA load with a 3.6V input voltage.

Figure 22. AS1334 - Functional Block Diagram

The size of the external components is reduced by using a high switching frequency (2MHz). Figure 1 on page 1

demonstrates that only three external power components are required for implementation. Also, the system controller

should set EN low during power-up and other low supply voltage conditions. See Shutdown Mode on page 12.

Mosfet

Control

Logic

Shutdown

Control

Main Control

Soft Start

Oscillator

Current

Sense

PVIN

VDD

FB

EN

SW

SGND

PGND

AS1334

POK

+

–

1.13V